Last Updated: 03/27/2021 @ 08:40 am
P0403 is a very common trouble code. It is a generic code, which means that it has the same meaning for the Nissan Maxima as it would any other vehicle. It affects the EGR (Exhaust Gas Recirculation System and technically means:
P0403: EGR→ Circuit Malfunction
A circuit malfunction implies that there is a wiring problem coming to or from the EGR system. That does not rule out the EGR solenoid itself. We’ll go into the most common symptoms and causes of P403 directly below.
As far as the average do it yourselfer being able to diagnose the cause of this code, it can be tricky since a good vehicle scanner and Ohm-meter can make the job a heck of a lot easier.
P0403 Symptoms: Nissan Maxima
Most of the time, there will be no noticeable symptoms accompanied with P0403, with the exception of the service engine soon light itself.
While not typical for any other symptoms to show with the P0403, it is possible that the Maxima will misfire if the EGR system is stuck open.
P0403 Causes
The issues that are going to cause P0403 are going to have to do with the EGR solenoid, or the wiring going to or from it. While it is possible for something else to cause P0403, these are far and away the most likely reasons for the code to populate
Bad EGR Solenoid
There’s going to be two issues that would cause the EGR solenoid not to operate, the solenoid itself, and the wiring going to it.
The EGR solenoid itself is often the cause of P0403. It can be checked with a good OBDII scanner and Ohm meter.
With the scanner, you’d want to command the EGR solenoid to operate. With the ohm meter hooked up, you should see movement on the gauge. If it’s not getting a signal, move on to the section directly below.
This video below is a great resource that’ll help you through the process of testing different EGR types.
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